High speed forging hammer apparatus



Sept. 30, 1969 TADASHI OIKAWA ETAL 3,469,400

HIGH SPEED FORGING HAMMER APPARATUS Filed June 3, 1968 2 Sheets-Sheet lp 0, 1969 TADASHI OIKAWA ETAL 3,469,400

HIGH SPEED FORGING HAMMER APPARATUS 2 Sheets-Sheet 2 Filed June 5. 1968FIGZ FIG.4

, INVENTORS? TADASHI OIKAWA HIROYASU YAG-UCHI' ATTORNEYS United StatesPatent 3,469,400 HIGH SPEED FORGING HAMMER APPARATUS Tadashi Oikawa andHiroyasu Yaguchi, Muroran, Japan, pssignors to Kabushiki Kaisha NihonSeikosho, Tokyo,

apan Continuation-impart of application Ser. No. 570,342, Aug. 4, 1966.This application June 3, 1968, Ser. No. 736,545 Claims priority,application Japan, Aug. 19, 1965,

0/ 50,139 Int. Cl. F01b 1/02; F1511 15/22 US. Cl. 60-57 4 ClaimsABSTRACT OF THE DISCLOSURE A high speed forging hammer apparatuscomprising a fluid pressure cylinder and a piston forming a part of aforging drop body. Two cylinder spaces separated by the pistoncommunicate with each other through a small hole extending through thepiston or through an external pipe. Both cylinder spaces and the hole orthe pipe are connected in a pressure line of a closed loop type throughwhich an operating fluid circulates.

This application is a continuation-in-part of application Ser. No.570,342, filed Aug. 4, 1966, now abandoned.

This invention relates in general to a high speed forging hammerapparatus and more particularly to a forging hammer apparatus capable ofeffecting high speed forging, precise forging and continuous forging.

The conventional type of forging hammers may be generally sorted intothree kinds; drop hammers utilizing direct mechanical forces, steamhammers utilizing steam,

and air hammers utilizing air. Among them, the air hammer is the mostwidely used type.

Air hammers utilize, as a power source, compressed air in an open loopsystem. Therefore, apart from a cooling loss in the associated aircompressor, an exhaust loss due to those portions of compressed airbeing exhausted during the lift and the drop strokes of a drop body isappreciable. Also, it is difficult to control the pressure of theoperating air, and among other drawbacks, the hammering force can not beproperly controlled through manual operation of a control valve.

Furthermore the conventional type of air hammer has been operated withair at a relatively low pressure and the hammering force depends uponboth the weight of the drop hammer involved and the length of its dropstroke. Under these circumstances, an increase in hammering forceinevitably leads to use of a large-sized machine. However, as mostcomponents of forging hammers are castings, their dimensions arenaturally limited. For this reason, it has heretofore been diflicult toproduce forging hammers with a high hammering force.

Accordingly, a general object of the invention is to eliminate the abovementioned difliculties.

An object of the invention is to provide a novel and improved high speedforging hammer apparatus operating with an operating fluid having acontrollable pressure with a very low exhaust loss and providing ahammering force precisely controllable at will under mechanical control.

Another object of the invention is to provide a novel and improved highspeed forging hammer apparatus relatively small in dimension and yethaving a greatly increased hammering force by increasing the fluidpressure and dropping a drop body at the maximum possible speed.

With the foresaid objects in view, the invention resides in a high speedforging hammer apparatus comprising a vertical operating cylindermember, a piston member ice slidable within the cylinder member anddividing the interior of the cylinder member into an upper cylinderspace and a lower cylinder space, the piston member forming a part of adrop body, and a fluid circulation system including the upper and lowercylinder spaces to drive the piston member, characterized in that meansare provided for communicating the upper cylinder space with the lowercylinder space, whereby the fluid circulation system is arranged to forma closed loop circuit.

In a preferred embodiment of the invention, a high speed forging hammerapparatus may comprise a vertical operating cylinder member, apistonmember vertically slidable within the cylinder member and dividing theinterior of the cylinder member into an upper cylinder space and a lowercylinder space, an upper piston rod projecting from the piston memberinto the upper cylinder space, a lower piston rod projecting from thepiston member into the lower cylinder member and further extendingexternally of the cylinder member, the upper piston rod being greater indiameter than the lower piston rod, a ram connected to the lower endportion of the lower piston rod, the piston, the upper and lower pistonrods, and the ram forming a drop body, a reservoir including a higherpressure chamber having fluid under a higher pressure contained thereinand a lower pressure chamber having fluid under a lower pressurecontained therein, a first duct means for connecting the upper cylinderspace with the higher pressure reservoir chamber, a control valvedisposed in the first duct means to control a flow of fluid under ahigher pressure into the upper cylinder space, second duct means forcommunicating the lower cylinder space with the lower pressure reservoirchamber, starting means responsive to the position of the piston memberto actuate the control valve and also to start the piston member, and acompressor means for pressurizing fluid from the lower pressurereservoir chamber and feeding the pressurized fluid into the higherpressure reservoir chamber, characterized in that piston member isprovided with a small hole axially extending therethrough to connect theupper cylinder space with the lower cylinder space, and that the higherpressure reservoir chamber, the first duct means, the upper cylinderspace, the hole in the piston member, the lower cylinder space, thesecond duct means, the lower pressure reservoir chamber and thecompressor means are arranged to form a closed loop circuit.

Alternatively, thes upper cylinder space may be connected with the lowercylinder through an external pipe instead of by the hole in the pistonmember. In order to control the rate at which the difference of pressurebetween the upper and lower cylinder space decreases and also to controlthe lifting speed of the piston member, a flow adjusting valve ispreferably disposed in the external pipe.

The invention, its organization and its mode of operation, as well asother objects and advantages thereof, will become more readily apparentfrom the following detailed description taken in conjunction with theaccompanying drawings in which:

FIG. 1 is a side elevational view, partly in longitudinal section, ofone embodiment of a high speedforging hammer apparatus according to theinvention;

FIGS. 2, 3 and 4 are fragmental sectional views illustrating relativepositions of the piston, cylinder, valve, etc. of the apparatus shown inFIG. 1 in different operating positions; and

FIG. 5 is a fragmental longitudinal sectional view of a modification ofthe invention.

Referring now to the drawings, and more particularly to FIG. 1, there isillustrated a high speed forging hammer apparatus embodying the featuresof the invention.

The arrangement illustrated comprises a pair of vertical frames and 11disposed symmetrically with respect to the longitudinal axis of theapparatus. The frames 10 and 11 can be made, for example, of a cast ironand their opposed internal side surfaces have disposed thereon a pair ofguide bars 12 and 13, respectively, which can be made, for example, of acast steel. The frames 10 and 11 are rigidly secured to an anvil block14 which, in turn, is disposed on a rigid foundation. Rigidly secured atthe upper ends of the frames 10 and 11 is a spacer plate or tie plate 16of cast iron upon which are mounted a vertical operating cylinder unitcomprising a cylinder body 18 and a cylinder cap 20 secured thereto.Thus the interior or cylinder chamber of the cylinder body 18 is closedat both ends except in the regions of piston rods which will besubsequently described.

Slidably fitted into the cylinder chamber 18 is a piston 22 whichdivides the cylinder chamber into an upper and a lower cylinder space 24and 25. The piston 22 is provided on the upper surface thereof with anupper piston rod 26 extending through the cylinder cap 20 and similarlyon the lower surface with a lower piston rod 27 extending through thelower cylinder space and slidably extending through the bottom of thecylinder chamber until it projects into a space between the frames 10and 11. The lower piston rod 27 has secured on the lower end portion aram 28 which in turn has on its lower end an upper tap 30. The ram 28can be made, for example, of a cast steel and is adapted to be guidedalong the guide bars 12 and 13 on the side frame surfaces. Thus it willbe appreciated that the piston 22, the upper and lower piston rods 26and 27, respectively, and the ram 28 are connected together to form adrop body. It is to be noted that the upper piston rod 26 is longer indiameter than the lower piston rod 27 and therefore that the piston 22has a smaller upper surface in pressure receiving area than the lowersurface, for a reason which will be described hereinafter.

A stationary lower tap 32 is rigidly secured on the anvil block 14 insuch a position that the drop body can strike the same.

In order to prevent an operating fluid under pressure from passing fromthe upper cylinder space 24 to the lower cylinder space 25 and viceversa through an annular clearance between the sliding cylindricalsurface of the piston 22 and the adjacent portion of the internalperipheral surface of the cylinder 18, the sliding surface of the pistonis provided with a set of piston rings 34 of conventional construction.Also, in order to prevent the fluid from leaking from the cylinderchamber through both ends, upper and lower packings 26 and 27,respectively, are disposed on the cylinder cap 20 and the bottom of thecylinder chamber 18 around those portions of the upper and lower pistonrods 26 and 27 extending through the latter.

As shown in FIG. 1, the upper end surface of the piston 22 is recessedat 38 except for the outermost annular portion, that annular portionadjacent the sliding surface providing an annular land 40 for a reasonwhich will be apparent hereinafter. Bored in the recessed portion 38 isa small hole 42 extending axially through the piston 22 for a purposewhich will be described later.

As also shown in FIG. 1, the lower surface of the cylinder cap 20forming the upper end surface of the cylinder is provided with anannular seat 44 in such a position that when the piston 20 reaches itsuppermost position, the annular land 40 on the piston 22 rests againstthe seat 44, thereby acting in a manner resembling a valve in the closedposition.

Mounted on the lower side of the cylinder cap 20 is a high pressureannular chamber 46 extending around the upper end portion of thecylinder chamber 18. The annular chamber 46 has formed on the internalwall surface a plurality of circumferentially spaced entrance ports 48opening into the cylinder chamber 18. The entrance ports 48 servenormally to connect the annular chamber 46 with the cylinder chamber 18,but they are adapted to be closed by the upper end portion of the piston22 only when the latter is located at its uppermost position. Disposedwithin the annular chamber 46 is a control valve 50 for controlling aflow of fluid under pressure through a valve port 52 into the annularchamber 46.

The cylinder body 18 has formed in the lower end portion a dischargeport 54 through which the fluid can be discharged from the lowercylinder space 25.

As shown in FIG. 1, an inverted Vshaped bracket 56 is rigidly secured onthe upper surface of the cylinder cap 20 and is provided on its flatapex with a starting device 58, which may be of a conventional design.The starting device 58 includes a feeler 60 projecting between the twolegs of the V and adapted to contact the upper end of the upper rod 26when the drop body reaches its uppermost position. This device isadapted to be externally operated to start the piston 22.

As shown in FIG. 2, a pair of solenoid valves 81 and 82 are forsupplying fluid to close the control 50 and to supply fluid to thefeeler 60 of the starting device 58 to cause the feeler to exert adownwardly directed force by a fluid pressure. A sensing means such as alimit switch 83 is provided on the inner surface of the top of bracket56 to sense the return of the drop body to its uppermost position. Thelimit switch is connected to the solenoid valve 82 to energize it to aposition to open valve 50. The solenoid valve 81 has a timer 81aconnected thereto to reset valve 81 automatically to the position todisconnect pressure fluid from feeler 60.

In order to operate the forging hammer unit as above described a fluidreservoir generally designated by the reference numeral 62 is disposedon a concrete foundation 64 and externally of the forging hammer unit.The reservoir 62 includes a lower pressure chamber 66 containing a fluidunder a lower pressure and a higher pres sure chamber 67 containing thefluid under a higher pressure. The lower pressure chamber 66 includes anentrance port 68 connected to the discharge port 54 on the cylinder by aduct 69 and an exit port 70 connected to a high pressure compressor 72on the suction side through a discharge port 71. The higher pressurechamber 67 includes an entrance port 74 connected to the discharge sideof the compressor 72 by a pipe 75 and a delivery port 76 connected tothe valve port 52 by a duct 77.

From the foregoing, it should be appreciated that the fluid circulatingsystem can be traced from the higher pressure reservoir chamber 67through the duct 77, the control valve 50, the upper cylinder space 24,the hole 42 in the piston 22, the lower cylinder space 25, the duct 69,the lower pressure reservoir chamber 66 and the pipe 71 to thecompressor 72 where the fluid is pressurized, and thence to the higherpressure reservoir 67 through the duct 77, these elements forming aclosed loop circuit by which the invention is characterized.

As in the conventional type of air forging hammer apparatus, the lowerpressure reservoir chamber 66 includes a fluid replenishing port andeach of the reservoir chambers 66 and 67 has various suitableconnections for a manometer and a safety valve, although thesecomponents are not illustrated in FIG. 1 for purpose of simplification.

The apparatus above described is operated as follows: It is assumed thatthe high pressure compressor 72 is always in operation to suck a fluidunder a lower pressure within the lower pressure reservoir chamber 66into the same and to pressurize the fluid which, in turn, is dischargedinto the higher pressure reservoir chamber 67 as an operating fluidunder a higher pressure. It is also assumed that the compressor 72includes a control means (not shown) for setting any desired dischargepressure and that the higher pressure reservoir chamber 67 has asufliciently high capacity. Under these assumed conditions, theoperating fluid has the pressure always maintained substantially at thepreset magnitude and is prevented from exceeding that magnitude.Further, it is assumed that the closed loop type fluid circulation system is filled with a predetermined volume of operating fluid and thatthe lower pressure reservoir chamber 66 has a sufficiently highcapacity. Therefore the fluid under the lower pressure is maintainedconstant in volume. It should be understood that, in order to compensatefor spontaneous leakage of the fluid, the latter can be replenished fromtime to time, thereby to prevent any decrease in fluid pressure.

One cycle of operation will now be described in conjunction with FIGS. 1to 4 inclusive. FIG. 3 illustrates the drop body comprising the piston22, the upper and lower piston rods 26 and 27, respectively, and therain 28 at the limit of the lift stroke or its uppermost position. Inthe position illustrated, the control valve 50 is in its closed positionand the pressures exerted on the upper and lower surfaces of the piston22 are equal to the pressure of fluid under the lower pressure becauseboth sides of the piston 22 are in communication with each other throughthe small hole 42. Therefore the piston 22 has exerted thereon anupwardly directed force equal in magnitude to the lower fluid pressuremultiplied by the difference between pressure receiving areas of theupper and lower piston surfaces, which are different because of thedifference in diameter of the upper and lower piston rods 25 and 26. Themagnitude of that force is preselected to 'be sufficiently great toovercome the total weight of the drop body, 22, 26, 27, 28. Thedifference between the force acting on the piston and the total weightof the drop body serves effectively to press the annular land 40 againstthe annular seat 44 ensuring sealing therebetween.

The feeler 60 on the starting device 58 is raised by the drop body atthe limit of its lift stroke, being moved upwardly from the FIG. 1 tothe FIG. '2 posit on, the fluid therein being discharged through thesolenoid valve 81. Limit switch 83 energizes solenoid valve 82,supplying pressure fluid to control valve 50 to cause the control valve50 to open. This opening of the valve 50 permits the fluid under thehigher pressure to fill the annular chamber 46. At that time, the fluidpressure will exert on the piston 22 a force tending to cause the latterto descend, but it is not sufficiently high to overcome the upwardlydireced force as described above. his causes the piston 22 to remain atits uppermost position.

The solenoid valve 81 is then energized, for example, by manuallyclosing switch 81b, to supply fluid under pressure to device 58 to movethe feeler 60 to slightly depress the drop body 22, 26, 27, 28 againstthe aboye mentioned force acting on the annular land 40. Tue relativepositions of the components at that instant are illustrated in FIG. 3.It is now assumed that this downwardly directed force is higher than theupwardly directed force of the drop body, and therefore serves toslightly depress the body.

As shown in FIG. 3, the pressure from the annular chamber 46 is appliedto the entire area of the upper piston surface to cause the drop body todrop at a high speed. As the drop body descends, the fluid within theupper cylinder space 24 is progressively expanded thereby to decreaseits pressure. In addition, a portion of the fluid within the uppercylinder space 24 flows into the lower cylinder space 25 through thesmall hole 42. The fluid in the lower cylinder space 25 flows into thelower pressure reservoir chamber 66. Eventually the drop body reachesthe lower limit of its descending stroke whereupon it imparts animpulsive force to a workpiece to be forged while at the same time thedrop body is deprived of its descending velocity thereby to stopinstantly.

At a time at which the drop body has dropped to complete the forgingoperation, the solenoid valve 81 is instructed to be reset by the timer81a, e.g. by the timer opening switch 81b. This causes the startingdevice 58 to return to its original position and permits the feeler 60to be raised freely. When the drop body has returned to its Originalraised position, the feeler 60 is raised by the action of the upwardlydirected force exerted by the drop body. The limit switch 83 will openas soon as the drop body starts down, thus deenergizing solenoid valve82 and closing control valve 50. When the drop body has returned to itsoriginal position, the switch 83 will automatically supply a signal tothe solenoid valve 82 to open control valve 50. The apparatus is thenready for another cycle upon operation of switch 81b.

From the foregoing, it will be appreciated that the impulsive force foruse in forging depends mainly upon the pressure and quantity of thefluid under the high pressure rather than upon the weight of the dropbody. As previously described, the pressure and quantity of the fluidunder the higher pressure remain unchanged and can readily becontrolled. Therefore the forging energy can readily be held at itspreselected magnitude.

FIG. 4 illustrates the position of the drop body as it just reaches itslowermost position in which it stops instantly. At the instant the dropbody has stopped, the fluid pressure on the upper piston surface is notequal to that on the lower piston surface. However, as the upper andlower cylinder spaces 24 and 25 communicate with each other through thesmall hole 42, the difference between pressures in the two spacesgradually decreases and the pressure difference becomes zero after ashort period of time. Therefore, the lower surface of the piston 22having the greater pressure receiving area has an upwardly directedforce applied thereto due to the difference of the pressure areas on theupper and lower piston surfaces, whereby the drop body is lifted untilit returns to its initial position illustrated in FIG. 2, whereupon onecycle of operation is completed. Thereafter, the cycle of operation asdescribed above is repeated until the forging operation is completed.

Referring now to FIG. 5, the same reference numerals designatecomponents identical to those illustrated in FIG. 1. In FIG. 5, the hole42 through the piston 22 is omitted, and a separate connecting pipe 78is provided for connecting the upper cylinder space 24 with the lowercylinder space 25. More specifically, the connecting pipe 78 opens atone end through the upper end face of the upper cylinder space 24 and atthe other end through the lower end portion of the lower cylinder space25. It is noted that with the piston 22 in its lowermost position, thepipe 78 still communicates with the lower cylinder space 25. Preferablythere is disposed in the pipe 28 a flow adjusting valve to adjust theflow of fluid through the latter to control the rate at which thepressure differential between the cylinder spaces decreases and thespeed at which the drop body 22, 26, 27, 28 is lifted. Other parts areidentical to those in FIG. 1. Therefore, the apparatus is operated inthe same manner as previously described in conjunction with FIGS. 2 to 4inclusive. If desired, the valve may be replaced by a suitable orifice.Alternatively, the valve may be omitted.

The invention has several advantages. For example, the use of a closedloop type fluid circulation system utilizing a fluid under high pressureleads to a minimum exhaust loss and a maximum speed of the drop bodyresulting in high speed forging. Further, the apparatus can berelatively small in size and yet provide a high forging energy. The highspeed of the apparatus permits a workpiece to be in contact with theassociated forging die for a minimum possible period of time. Thistogether with the controllability of the capability of the apparatusenable a precise forging, and the decreases in the periods of timeduring which the drop body is lifted and the fluid under the highpressure fills the annular chamber ensures continuous forging, as willbe readily understood from the foregoing description.

While the invention has been illustrated and described in conjunctionwith two embodiments thereof, it should be understood that variouschanges and modifications may be resorted to without departing from thespirit and scope of the invention.

What we claim is:

1. A high speed forging hammer apparatus comprising a vertical operatingcylinder, a piston member vertically slidable within the cylinder memberand dividing the interior of said cylinder member into an upper cylinderspace and a lower cylinder space, an upper piston rod projecting fromsaid piston member into the upper cylinder space, a lower piston rodprojecting from said piston member into the lower cylinder member andfurther extending externally of the cylinder member, said upper pistonrod being greater in diameter than said lower piston rod, a hammer tapconnected on the lower end portion of said lower piston rod, saidpiston, said upper and lower piston rods, and said hammer tap forming adrop body, a reservoir including a higher pressure chamber having fluidunder higher pressure contained therein and a lower pressure chamberhaving fluid under lower pressure contained therein, a first duct meansconnecting said upper cylinder space with said higher pressure reservoirchamber, a control valve disposed in said first duct means to control aflow of fluid under higher pressure into said upper cylinder Space,second duct means connecting said lower cylinder space with said lowerpressure reservoir chamber, starting means responsive to the position ofsaid piston member to actuate said control valve and also to give aninitial movement to said piston member, and compressor means connectedbetween said lower pressure reservoir chamber and higher pressurereservoir chamber for pressurizing fluid from said lower pressurereservoir chamber and feeding the pressurized fluid into said higherpressure reservoir chamber, the piston member having a small holeaxially extending therethrough to place said upper cylinder space incommunication with said lower cylinder space, and said higher pressurereservoir chamber, said first duct means, said upper cylinder space,said small hole in the piston member, said lower cylinder space, saidsecond duct means, said lower pressure reservoir chamber and saidcompressor means forming a closed loop circuit.

2. A high speed forging hammer apparatus comprising a vertical operatingcylinder member, a piston member vertically slidable within saidcylinder member and dividing the interior of the cylinder member into anupper cylinder space and a lower cylinder space, an upper piston rodprojecting from said piston member into th I upper cylinder space, alower piston rod projecting from said piston member into the lowercylinder member and further extending externally of the cylinder member,said upper piston rod being greater in diameter than said lower pistonrod, a hammer tap connected on the lower end portion of said lowerpiston rod, said piston, said upper and lower piston rods, and said ramforming a drop body, a reservoir includind a higher pressure chamberhaving fluid under higher pressure contained therein and a lowerpressure chamber having fluid under lower pressure contained therein, afirst duct means connecting said upper cylinder space with said higherpressure reservoir chamber, a control valve disposed in said first ductmeans to control a flow of fluid under higher pressure into said uppercylinder space, second duct means connecting said lower cylinder spacewith said lower pressure reservoir chamber, starting means responsive tothe position of said piston member to actuate said control valve andalso to give an initial movement to said piston member, compressor meansconnected between said lower pressure reservoir chamber and said higherpressure reservoir chamber for pressurizing fluid in said lower pressurereservoir chamber and feeding the pressurized fluid into said higherpressure reservoir chamber, and a connecting pipe connected at one endto the upper end surface of said upper cylinder space and at the otherend to the lower portion of said lower cylinder space, said higherpressure reservoir chamber, said first duct means, said upper cylinderspace, said connecting pipe, said lower cylinder space, said second ductmeans, said lower pressure reservoir chamber and said compressor meansforming a closed loop circuit.

3. A high speed forging hammer apparatus as claimed in claim 2 whereinsaid conducting pipe has therein an adjusting valve to control a flow offluid therethrough.

4. A high speed forging hammer apparatus comprising a vertical operatingcylinder, a piston member vertically slidable within the cylinder memberand dividing the interior of said cylinder member into an upper cylinderspace and a lower cylinder space, an upper piston rod projecting fromsaid piston member into the upper cylinder space, a lower piston rodprojecting from said piston member into the lower cylinder member andfurther extending externally of the cylinder member, said upper pistonrod being greater in diameter than said lower piston rod, a hammer tapconnected on the lower end portion of said lower piston rod, saidpiston, said upper and lower piston rods, and said hammer tap forming adrop body, a closed pressure fluid circulating system including areservoir including a higher pressure chamber having fluid under higherpressure contained therein and a lower pressure chamber having fluidunder lower pressure contained therein, a pressure increasing meansconnected between said chambers, said upper cylinder space beingconnected with said higher pressure reservoir chamber and the lowercylinder space being connected with said lower pressure reservoirchamber, a control valve means coupled between said higher pressurereservoir chamber and said upper cylinder space for controlling flow offluid under higher pressure into said upper cylinder space, startingmeans responsive to the position of said piston member to actuate saidcontrol valve and also to give an initial movement to said pistonmember, a constantly open conduit means between said upper and lowercylinder spaces placing said upper cylinder space in communication withsaid lower cylinder space, and said higher pressure reservoir chamber,said upper cylinder space, said open conduit means, said lower cylinderspace, and said lower pressure reservoir chamber forming a closed loopcircuit.

References Cited UNITED STATES PATENTS 513,601 1/1894 Teal 914l61,897,581 2/1933 McNab 9l416 2,742,879 3/ 1953 Kieser.

2,902,007 9/1959 Rockwell 91-401 2,954,755 10/ 1960 Pecchenino.3,115,676 12/1963 Quartullo 91-416 PAUL E. MASLOUSKY, Primary ExaminerUS. Cl. X.R.

